There are 13 US Post Offices in Klickitat County serving a total of 20,187 residents equating to 1,553 residents per post office. It's estimated that approximately 32,221 packages are handled across the 13 county post offices annually. Klickitat County is a county located in the U.S. state of Washington. As of the 2010 census, the population was 20,318. The county seat and largest city is Goldendale. The county is named after the Klickitat tribe of the Yakama Native Americans."